Mac display dimming and brightening

macmaniac

Hi folks,
Please help. The display on my 2017 MBP(13.6.7) is dimming and brightening(10-15%) every 1 to 2 seconds when an app is active, sometimes with noticeable vertical lines. Just prior to this happening I removed two pics which were alternating/rotating as desktop background wallpaper; related? It does not do this while cursor is moving or when only the desktop is on screen. Thank you.

marvin

macmaniac said:

Hi folks,
Please help. The display on my 2017 MBP(13.6.7) is dimming and brightening(10-15%) every 1 to 2 seconds when an app is active, sometimes with noticeable vertical lines. Just prior to this happening I removed two pics which were alternating/rotating as desktop background wallpaper; related? It does not do this while cursor is moving or when only the desktop is on screen. Thank you.

Sometimes visuals can mess up like this if the graphics chip goes bad. If you have a 15" model, they have two GPUs and one can go bad so you get artifacts when it switches to the bad GPU.

Brightness issues can be due to a bad display cable or backlight. Check if the lines change when rotating the display.

If you boot into safe mode (hold shift-key when booting), check if it does the same.

edited June 2024

macmaniac

Thanks for your response, Marvin. I have a 13 inch. In safe mode it was OK but it came back upon next normal boot-up. It stops when display is rotated or cursor is moved, then returns.

marvin

macmaniac said:

Thanks for your response, Marvin. I have a 13 inch. In safe mode it was OK but it came back upon next normal boot-up. It stops when display is rotated or cursor is moved, then returns.

Safe mode disables the GPU. Since it's ok in safe mode, that would suggest the GPU over the display connection but there are a few videos about the 2017 model to do with the display cable and the description sounds similar to this:



There was a repair program for the issue but this has ended:

https://www.ifixit.com/News/16943/macbook-pro-flexgate-repair-program

Getting it repaired at a store would be an option but there are a couple of alternatives. One would be to use an external display. If it needs to be portable, there are portable displays:

https://www.amazon.com/Intehill-Portable-13-3-inch-Response-External/dp/B0C65SJ1NZ
https://www.amazon.com/VILVA-Portable-Monitor-Laptop-Portable-Speakers/dp/B0BTSFVMLV

A new laptop would be best, the new Apple Silicon ones are much better than the Intel ones. A brand new Macbook Air 13" 16GB/512GB would be $1399-1499 but some old refurbs are less:

https://www.ebay.com/itm/235640617007 (M1 $695)
https://www.ebay.com/itm/285848592697 (M1 $769)
https://www.ebay.com/itm/226170782516 (M1 $879)

The model you have can be replaced for under $400 but these models have the same defects with the cables so it would be best getting a newer model:

https://www.ebay.com/itm/256481877767
https://www.ebay.com/itm/186514879745